Explanation:
What's happening in the eye-like center of this
planetary nebula?
The geometry revealed in this Hubble Space Telescope view of the central part of
an "etched hourglass nebula"
known as MyCn 18
presents a puzzle.
First, the axis of this central region does not line up well with the
outer hourglass structure.
Next, the
hot star (the white spot to the left of center) which ejected this
gaseous nebula as it evolved towards its
white dwarf phase,
is not exactly at the center of the "eye".
These unexpected results leave astronomers looking for the missing
pieces of the ejection process that created this
unusual and beautiful structure.